This application is based on Application No. 2001-108447, filed in Japan on Apr. 6, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a stator for a dynamoelectric machine such as automotive alternators, etc, and particularly to a stator construction for improving cooling in a joint portion of a conductor wire constituting a stator winding.
2. Description of the Related Art
FIG. 24 is a longitudinal section showing a first conventional automotive alternator, and FIG. 25 is a perspective showing a conductor segment used in a stator winding of a stator mounted to the first conventional automotive alternator. FIG. 26 is a rear end elevation schematically showing a first winding phase portion of the stator winding of the stator mounted to the first conventional automotive alternator. In FIG. 26, solid lines indicate rear-end wiring, broken lines indicate front-end wiring, and black circles indicate joint portions. FIG. 27 is a diagram schematically showing a rear-end portion of the stator in the first conventional automotive alternator viewed from a circumferential direction, FIG. 28 is a side elevation showing the rear-end portion of the stator mounted to the first conventional automotive alternator viewed from radially outside, and FIG. 29 is an end elevation showing the rear-end portion of the stator mounted to the first conventional automotive alternator viewed from axially outside. Moreover, in FIG. 24, the shapes of coil ends are represented schematically.
As shown in FIG. 24, a first conventional automotive alternator includes: a case 3 constituted by a front bracket 1 and a rear bracket 2 made of aluminum; a shaft 6 disposed inside the case 3, a pulley 4 being secured to a first end portion of the shaft 6; a Lundell-type rotor 7 secured to the shaft 6; fans 5 secured to first and second axial end portions of the rotor 7; a stator 8 secured to the case 3 so as to envelop the rotor 7; slip rings 9 secured to a second end of the shaft 6 for supplying electric current to the rotor 7; a pair of brushes 10 sliding on surfaces of the slip rings 9; a brush holder 11 accommodating the brushes 10; rectifiers 12 each having a rectifier heat sink 12a, the rectifiers 12 being electrically connected to the stator 8 to convert alternating current generated in the stator 8 into direct current; and a regulator 18 mounted to a brush holder heat sink 17 fitted onto the brush holder 11, the regulator 18 adjusting the magnitude of the alternating voltage generated in the stator 8.
The rotor 7 includes: a field winding 13 for generating magnetic flux on passage of an electric current; and a pair of first and second pole cores 20 and 21 disposed so as to cover the field winding 13, magnetic poles being formed in the first and second pole cores 20 and 21 by magnetic flux therefrom. The first and second pole cores 20 and 21 are made of iron, each has a plurality of first and second claw-shaped magnetic poles 22 and 23 having a generally trapezoidal outermost diameter surface shape disposed on an outer circumferential edge portion at even angular pitch in a circumferential direction so as to project axially, and the first and second pole cores 20 and 21 are fixed to the shaft 6 facing each other such that the first and second claw-shaped magnetic poles 22 and 23 intermesh.
The stator 8 is constituted by: a cylindrical stator core 15; and a stator winding 16 installed in the stator core 15. The stator 8 is held between the front bracket 1 and the rear bracket 2 so as to form a uniform air gap between outer circumferential surfaces of the claw-shaped magnetic poles 22 and 23 and an inner circumferential surface of the stator core 15.
Here, a specific construction of the stator winding 16 will be explained with reference to FIGS. 25 and 27.
First, a conductor segment 30 is prepared by bending into a general U shape a short length of a copper wire material having a circular cross section covered with an electrically-insulating coating. As shown in FIG. 25, this conductor segment 30 is constituted by a general U shape in which a pair of straight portions 30a are linked by a turn portion 30b. 
The stator core 15 is prepared by laminating a predetermined number of long, thin magnetic steel plates in which slots 15a are formed at a predetermined pitch, bending the laminated body into an annular shape with the openings of the slots 15a facing an inner circumferential side, and welding first and second end surfaces of the annular shape. In this stator core 15, the slots 15a, which have grooves lying in an axial direction, are formed at a ratio of two per phase per pole. In other words, ninety-six slots 15a are arranged circumferentially on an inner circumferential side of the stator core 15, the number of magnetic poles in the rotor 7 being sixteen.
Moreover, to facilitate explanation, Slot Numbers from 1 to 96 are allocated to each of the slots 15a as shown in FIG. 26, and the positions in each of the slots 15a in which the conductor segments 30 are housed are designated Address 1, Address 2, Address 3, and Address 4, respectively, from an inner circumferential side.
Conductor segments 30 are inserted two at a time from a front end of the stator core 15 into slot pairs separated by six slots (slot pairs including Slot Numbers n and (n+6)). Here, in each of the slot pairs, a first conductor segment 30 is inserted into Address 1 in slot 15a Number n and into Address 2 in slot 15a Number (n+6) and a second conductor segment 30 is inserted into Address 3 in slot 15a Number n and into Address 4 in slot 15a Number (n+6). The free end portions of the conductor segments 30 extending outward at the rear end from Address 1 and Address 2 of each of the slot pairs are bent in a clockwise direction in FIG. 26, and the free end portions of the conductor segments 30 extending outward at the rear end from Address 3 and Address 4 of each of the slot pairs are bent in a counterclockwise direction in FIG. 26. Here, four straight portions 30a are housed in each of the slots 15a so as to line up in one row in a radial direction.
Next, the free end portions 30c of the conductor segments 30 extending outward at the rear end from Address 1 in slot 15a Number n and the free end portions 30c of the conductor segments 30 extending outward at the rear end from Address 4 in slot 15a Number (n+6) are stacked in a radial direction and joined by welding, etc. Similarly, the free end portions 30c of the conductor segments 30 extending outward at the rear end from Address 2 in slot 15a Number n and the free end portions 30c of the conductor segments 30 extending outward at the rear end from Address 3 in slot 15a Number (n+6) are stacked in a radial direction and joined by welding, etc. Thus, two two-turn lap windings are formed, the lap windings being wound into every sixth slot 15a. 
Now, at the rear end of the stator core 15, distant-address joint portions 311-4 joining the free end portions 30c of the conductor segments 30 extending outward at the rear end from Address 1 and Address 4 in each of the slot pairs surround near-address joint portions 312-3 joining the free end portions 30c of the conductor segments 30 extending outward at the rear end from Address 2 and Address 3 as shown in FIGS. 27 to 29. Thus, the two joint portions 311-4 and 312-3 are arranged into two layers in an axial direction.
Similarly, at the front end of stator core 15, the turn portions 30b of the conductor segments 30 extending outward at the front end from Address 1 and Address 2 in each of the slot pairs and the turn portions 30b of the conductor segments 30 extending outward at the front end from Address 3 and Address 4 are arranged so as to overlap in a radial direction.
Next, for example, the free end portion 30c of the conductor segment 30 extending at the rear end from Address 2 of slot 15a Number 91 and the free end portion 30c of conductor segment 30 of slot 15a Number 1 extending at the rear end from Address 4 are joined. Thus, as shown in FIG. 26, a first four-turn winding phase portion 161 is prepared by connecting two two-turn lap windings in series. The free end portion 30c of the conductor segment 30 extending outward at the rear end from Address 1 of slot 15a Number 91 becomes an output wire (O) of the first winding phase portion 161, and the free end portion 30c of the conductor segment 30 extending outward at the rear end from Address 3 of slot 15a Number 1 becomes a neutral-point lead wire (N) of the first winding phase portion 161.
Here, only the first winding phase portion 161, which is installed in a first slot group including Slot Numbers 1, 7, etc., through 91, is shown in FIG. 26, but second to sixth winding phase portions 161 are similarly installed in a second slot group including Slot Numbers 2, 8, etc., through 92, a third slot group including Slot Numbers 3, 9, etc., through 93, a fourth slot group including Slot Numbers 4, 10, etc., through 94, a fifth slot group including Slot Numbers 5, 11, etc., through 95, and a sixth slot group including Slot Numbers 6, 12, etc., through 96, respectively.
A first three-phase alternating-current winding is prepared by connecting together each of the neutral-point lead wires (N) of the first, third, and fifth winding phase portions 161 installed in the first slot group including Slot Numbers 1, 7, etc., through 91, the third slot group including Slot Numbers 3, 9, etc., through 93, and the fifth slot group including Slot Numbers 5, 11, etc., through 95, respectively, to form the first, third, and fifth winding phase portions 161 into a Y connection (an alternating-current connection). Similarly, a second three-phase alternating-current winding is prepared by connecting together each of the neutral-point lead wires (N) of the second, fourth, and sixth winding phase portions 161 installed in the second slot group including Slot Numbers 2, 8, etc., through 92, the fourth slot group including Slot Numbers 4, 10, etc., through 94, and the sixth slot group including Slot Numbers 6, 12, etc., through 96, respectively, to form the second, fourth, and sixth winding phase portions 161 into a Y connection (an alternating-current connection). The stator winding 16, which is composed of the first and second three-phase alternating-current windings constructed in this manner, is installed in the stator core 15 to obtain the stator 8.
The stator 8 prepared in this manner is mounted to an automotive alternator, the first and second three-phase alternating-current windings each being connected to different rectifiers 12. Thus, outputs from the first and second three-phase alternating current windings are subjected to three-phase full-wave rectification in different rectifiers 12, then combined and output.
In the stator 8 constructed in this manner, as shown in FIGS. 27 to 29, the distant-address joint portions 311-4 and the near-address joint portions 312-3 joining together the free end portions 30c of the conductor segments 30 are arranged at a predetermined pitch in a circumferential direction so as to form two layers in an axial direction, constituting a rear-end coil end group 16r. Moreover, although not shown, the turn portions 30b of the conductor segments 30 are arranged at a predetermined pitch so as to line up in single rows separated by a predetermined distance in a radial direction and to form two rows in a circumferential direction, constituting a front-end coil end group 16f. 
In the automotive alternator constructed in this manner, an electric current is supplied from a battery (not shown) through the brushes 10 and the slip rings 9 to the field winding 13, generating a magnetic flux. The first claw-shaped magnetic poles 22 on the first pole core 20 are magnetized into North-seeking (N) poles by this magnetic flux, and the second claw-shaped magnetic poles 23 on the second pole core 21 are magnetized into South-seeking (S) poles.
At the same time, the pulley 4 is driven by an engine and the rotor 7 is rotated by the shaft 6. A rotating magnetic field is applied to the stator core 15 due to the rotation of the rotor 7, generating an electromotive force in the stator winding 16. Then, the alternating electromotive force generated in the stator winding 16 is converted into direct current by the rectifiers 12 and the magnitude of the output voltage thereof is adjusted by the regulator 18, recharging the battery.
Now, the field winding 13, the stator winding 16, the rectifiers 12, and the regulator 18 constantly generate heat during power generation.
Thus, in order to dissipate the heat generated by power generation, front-end and rear-end air intake apertures 1a and 2a are disposed through axial end surfaces of the front bracket 1 and the rear bracket 2, and front-end and rear-end air discharge apertures 1b and 2b are disposed through radial side surfaces of the front bracket 1 and the rear bracket 2 so as to face coil end groups 16f and 16r of the stator winding 16.
Thus, the fans 5 are rotated and driven together with the rotation of the rotor 7, and cooling airflow channels are formed in which external air is sucked inside the case 3 through the front-end and rear-end air intake apertures 1a and 2a, flows axially towards the rotor 7, is then deflected centrifugally by the fans 5, thereafter crosses the coil end groups 16f and 16r, and is discharged outside through the front-end and rear-end air discharge apertures 1b and 2b. As a result of a pressure difference between a front end and a rear end of the rotor 7, a cooling airflow channel is also formed in which cooling air flows through the inside of the rotor 7 from the front end to the rear end.
As a result, heat generated in the stator winding 16 is dissipated from the coil end groups 16f and 16r to the cooling airflows, suppressing temperature increases in the stator 8. Heat generated in the rectifier 12 and the regulator 18 is dissipated to a cooling airflow by means of the rectifier heat sink 12a and the brush holder heat sink 17, thereby suppressing temperature increases in the rectifier 12 and the regulator 18. In addition, heat generated in the field winding 13 is dissipated to the cooling airflow which flows through the inside of the rotor 7, thereby suppressing temperature increases in the rotor 7.
In the first conventional stator 8 described above, because the stator winding 16 is prepared by installing a large number of the conductor segments 30 in the stator core 15 and joining the free end portions of the conductor segments 30, one problem has been that the number of joints is large, causing assembly of the stator winding 16 to deteriorate significantly. The joint portions 311-4 and 312-3 joining the conductor segments 30 are also softened by welding, causing rigidity of the stator winding 16 to deteriorate. Thus, another problem is that magnetic noise increases when rigidity of the stator 8 has deteriorated and the stator 8 is mounted to an automotive alternator.
In order to solve such problems, a stator winding construction has been proposed by the present applicants in Japanese Patent Non-Examined Laid-Open No. 11-361286, for example, enabling assembly of the stator winding to be improved and reductions in rigidity of the stator winding due to welding to be suppressed by preparing a stator winding using continuous conductor wires, thereby reducing the number of joints in the stator winding.
Next, a conventional stator construction using a stator winding prepared using continuous conductor wires will be explained.
FIG. 30 is a longitudinal section showing a second conventional automotive alternator, and FIG. 31 is a rear end elevation schematically showing a first winding phase portion of a stator winding of a stator mounted to the second conventional automotive alternator. In FIG. 31, solid lines indicate rear-end wiring, broken lines indicate front-end wiring, and black circles indicate joint portions. FIG. 32 is a diagram schematically showing a rear-end portion of the stator in the second conventional automotive alternator viewed from a circumferential direction, FIG. 33 is a side elevation showing the rear-end portion of the stator mounted to the second conventional automotive alternator viewed from radially outside, and FIG. 34 is an end elevation showing the rear-end portion of the stator mounted to the second conventional automotive alternator viewed from axially outside. Moreover, in FIG. 30, the shapes of coil ends are represented schematically.
In FIG. 30, a stator 8A has a stator winding 16A prepared using continuous conductor wires 32 installed in the stator core 15.
A winding construction of a first winding phase portion 162 of the stator winding 16A will now be explained in detail with reference to FIG. 31. Moreover, the continuous conductor wires 32 are prepared from a copper wire material having a rectangular cross section coated with an electrical insulator.
The first winding phase portion 162 is constituted by first to sixth winding sub-portions 34 to 39 each composed of one continuous conductor wire 32. The first winding sub-portion 34 is constructed by wave winding one continuous conductor wire 32 into every sixth slot from Slot Numbers 1 to 91 so as to alternately occupy Address 2 and Address 1 in the slots 15a. The second winding sub-portion 35 is constructed by wave winding a continuous conductor wire 32 into every sixth slot from Slot Numbers 1 to 91 so as to alternately occupy Address 1 and Address 2 in the slots 15a. The third winding sub-portion 36 is constructed by wave winding a continuous conductor wire 32 into every sixth slot from Slot Numbers 1 to 91 so as to alternately occupy Address 4 and Address 3 in the slots 15a. The fourth winding sub-portion 37 is constructed by wave winding a continuous conductor wire 32 into every sixth slot from Slot Numbers 1 to 91 so as to alternately occupy Address 3 and Address 4 in the slots 15a. The fifth winding sub-portion 38 is constructed by wave winding a continuous conductor wire 32 into every sixth slot from Slot Numbers 1 to 91 so as to alternately occupy Address 6 and Address 5 in the slots 15a. The sixth winding sub-portion 39 is constructed by wave winding a continuous conductor wire 32 into every sixth slot from Slot Numbers 1 to 91 so as to alternately occupy Address 5 and Address 6 in the slots 15a. In each of the slots 15a, the six continuous conductor wires 32 are arranged so as to line up in one row in a radial direction with longitudinal axes of their rectangular cross sections aligned radially.
At the rear end of the stator core 15, a first end portion 35a of the second winding sub-portion 35 extending outward from Address 1 of Slot Number 1 and a second end portion 39b of the sixth winding sub-portion 39 extending outward from Address 6 of Slot Number 91 are joined, a first end portion 37a of the fourth winding sub-portion 37 extending outward from Address 3 of Slot Number 1 and a second end portion 35b of the second winding sub-portion 35 extending outward from Address 2 of Slot Number 91 are joined, and a first end portion 39a of the sixth winding sub-portion 39 extending outward from Address 5 of Slot Number 1 and a second end portion 37b of the fourth winding sub-portion 37 extending outward from Address 4 of Slot Number 91 are joined to form a three-turn wave winding in which the second, fourth, and sixth winding sub-portions 35, 37, and 39 are connected in series.
At the front end of the stator core 15, a first end portion 34a of the first winding sub-portion 34 extending outward from Address 2 of Slot Number 1 and a second end portion 36b of the third winding sub-portion 36 extending outward from Address 3 of Slot Number 91 are joined, a first end portion 36a of the third winding sub-portion 36 extending outward from Address 4 of Slot Number 1 and a second end portion 38b of the fifth winding sub-portion 38 extending outward from Address 5 of Slot Number 91 are joined, and a first end portion 38a of the fifth winding sub-portion 38 extending outward from Address 6 of Slot Number 1 and a second end portion 34b of the first winding sub-portion 34 extending outward from Address 1 of Slot Number 91 are joined to form a three-turn wave winding in which the first, third, and fifth winding sub-portions 34, 36, and 38 are connected in series.
A portion of the continuous conductor wire 32 of the first winding sub-portion 34 extending outward at the rear end of the stator core 15 from Slot Numbers 49 and 55 is cut, and a portion of the continuous conductor wire 32 of the second winding sub-portion 35 extending outward at the rear end of the stator core 15 from Slot Numbers 55 and 61 is cut. A first cut end 34c of the first winding sub-portion 34 and a first cut end 35c of the second winding sub-portion 35 are joined to form a six-turn first winding phase portion 162 in which the first to sixth winding sub-portions 34 to 39 are connected in series.
Moreover, a second cut end 34d of the first winding sub-portion 34 and a second cut end 35d of the second winding sub-portion 35 become an output wire (O) and a neutral-point lead wire (N), respectively, of the first winding phase portion 162.
Here, only the first winding phase portion 162, which is installed in a first slot group including Slot Numbers 1, 7, etc., through 91, is shown in FIG. 31, but second to sixth winding phase portions 162 are similarly installed in a second slot group including Slot Numbers 2, 8, etc., through 92, a third slot group including Slot Numbers 3, 9, etc., through 93, a fourth slot group including Slot Numbers 4, 10, etc., through 94, a fifth slot group including Slot Numbers 5, 11, etc., through 95, and a sixth slot group including Slot Numbers 6, 12, etc., through 96, respectively.
A first three-phase alternating-current winding is prepared by connecting together each of the neutral-point lead wires (N) of the first, third, and fifth winding phase portions 162 installed in the first slot group including Slot Numbers 1, 7, etc., through 91, the third slot group including Slot Numbers 3, 9, etc., through 93, and the fifth slot group including Slot Numbers 5, 11, etc., through 95, respectively, to form the first, third, and fifth winding phase portions 162 into a Y connection (an alternating-current connection). Similarly, a second three-phase alternating-current winding is prepared by connecting together each of the neutral-point lead wires (N) of the second, fourth, and sixth winding phase portions 162 installed in the second slot group including Slot Numbers 2, 8, etc., through 92, the fourth slot group including Slot Numbers 4, 10, etc., through 94, and the sixth sot group including Slot Numbers 6, 12, etc., through 96, respectively, to form the second, fourth, and sixth winding phase portions 162 into a Y connection (an alternating-current connection). The stator winding 16A, which is composed of the first and second three-phase alternating-current windings constructed in this manner, is installed in the stator core 15 to obtain the stator 8A.
The first and second three-phase alternating current windings are each connected to separate rectifiers 12, and the direct-current outputs from each of the rectifiers 12 are connected in parallel and combined.
In the stator 8A constructed in this manner, as shown in FIGS. 32 to 34, turn portions 32a of the continuous conductor wires 32 are arranged at a predetermined pitch so as to line up in single rows separated by a predetermined distance from each other in a radial direction and to form three rows in a circumferential direction, constituting a rear-end coil end group 16r. In a connection portion of the continuous conductor wires 32 in the rear-end coil end group 16r (a portion in which the end portions of the continuous conductor wires 32 are joined together), a first near-address joint portion 312-3 joining the end portions of the continuous conductor wires 32 extending outward from Address 2 and Address 3 of slot pairs separated by six slots and a second near-address joint portion 314-5 joining the end portions of the continuous conductor wires 32 extending outward from Address 4 and Address 5 of the same slot pair line up in a radial direction, and a distant-address joint portion 311-6 joining the end portions of the continuous conductor wires 32 extending outward from Address 1 and Address 6 of the same slot pair is arranged so as to surround the first and second near-address joint portions 312-3 and 314-5 that are lined up in the radial direction. Six sets of the three types of joint portions 312-3, 314-5, and 311-6 constructed in this manner are arranged at a pitch of one slot in a circumferential direction.
Moreover, a front-end coil end group 16f is also constructed similarly.
Here, each of the continuous conductor wires 32 constituting the first to sixth winding sub-portions 34 to 39 is installed in a wave winding so as to extend outward from any given slot 15a at an end surface of the stator core 15, fold over, and enter a slot 15a six slots away. Each of the continuous conductor wires 32 is installed in every sixth slot so as to alternately occupy an inner layer and an outer layer in a slot depth direction (a radial direction).
The turn portions 32a of the continuous conductor wires 32 that extend outward from the end surfaces of the stator core 15 and fold over form coil ends. Thus, at first and second ends of the stator core 15, the turn portions 32a, which are formed into a substantially uniform shape, are separated from each other in a circumferential direction and a radial direction and are arranged neatly in a circumferential direction in three layers to form the coil end groups 16f and 16r. 
Next, a construction of a winding assembly used in the stator winding 16A of the second conventional stator 8A will be explained with reference to FIGS. 35A to 37.
FIGS. 35A and 35B are an end elevation and a side elevation, respectively, showing a winding assembly used in the stator winding described in Japanese Patent Non-Examined Laid-Open No. 11-361286, for example. FIG. 36 is a perspective showing part of a continuous conductor wire constituting the winding assembly shown in FIGS. 35A and 35B, and FIG. 37 is a diagram explaining arrangement of continuous conductor wires constituting the winding assembly shown in FIGS. 35A and 35B.
A winding assembly 33 is formed by arranging twelve continuous conductor wires 32 composed of a copper wire material having a rectangular cross section coated with an electrical insulator at a pitch of one slot on a plane and folding the twelve continuous conductor wires 32 simultaneously.
Thus, as shown in FIG. 36, each of the continuous conductor wires 32 is formed by bending into a planar pattern in which straight portions 32b linked by turn portions 32a are arranged at a pitch of six slots (6P). Adjacent pairs of the straight portions 32b are offset by the turn portions 32a by a width (w) of the continuous conductor wires 32 in a direction perpendicular to the direction of disposal of the straight portions 32b. Pairs of the continuous conductor wires 32 are formed by arranging two of the continuous conductor wires 32 formed in this pattern so as to be offset by a pitch of six slots with straight portions 32b stacked as shown in FIG. 37, and the winding assembly 33 shown in FIG. 35 is constructed by arranging six of these pairs so as to be offset by a pitch of one slot from each other.
Three winding assemblies 33 constructed in this manner are stacked radially and installed in the stator core 15 such that each of the pairs of straight portions 32b are inserted into each of the slots 15a. The stator 8A, in which is the stator winding 16A is installed in the stator core 15, is obtained by joining the first and second ends of each of the continuous conductor wires 32 of the winding assembly 33 based on the connection method shown in FIG. 31.
In the second conventional stator 8A constructed in this manner, because the stator winding 16A is prepared by mounting to the stator core 15 the winding assemblies 33 prepared using the continuous conductor wires 32, and joining together end portions of the continuous conductor wires 32, the number of joints is reduced significantly compared to the first conventional stator 8, significantly improving assembly of the stator winding 16A. Furthermore, even if the joint portions 312-3, 314-5, and 311-6 are softened by welding, reductions in the rigidity of the stator winding 16A are suppressed because the number of joint portions is small. Thus, reductions in rigidity of the stator 8A as a whole are suppressed, and when the stator 8A is mounted to an automotive alternator, increases in magnetic noise can be suppressed.
In the first stator 8 used in a conventional automotive alternator, as described above, the first stator winding 16 is prepared by inserting the conductor segments 30 formed into the general U shape two at a time into each of the slot pairs separated by six slots and joining together the free end portions 30c of the conductor segments 30. In the second stator 8A, the second stator winding 16A is prepared by winding a plurality of the continuous conductor wires 32 into a wave shape so as to alternately occupy an inner layer and an outer layer in every sixth slot 15a and joining together end portions of the continuous conductor wires 32.
Now, joining of the free end portions 30c of the conductor segments 30 and joining of the end portions of the continuous conductor wires 32 are performed by TIG welding and are accompanied by increases in resistance values in the joint portions 31 as a result of contamination by impurities during joining. Thus, the generation of heat in the joint portions 31 is at its greatest during energization of the first and second stator windings 16 and 16A. Furthermore, the electrically-insulating coating is removed from the joint portions 31, making it necessary to ensure electrical insulation between the brackets 1 and 2 and the joint portions 31 and electrical insulation among the joint portions 31.
In the first conventional stator 8, because the distant-address joint portions 311-4 and the near-address joint portions 312-3 are arranged at a predetermined pitch in a circumferential direction so as to stack up in two layers in an axial direction and constitute the rear-end coil end group 16r, axial height of the rear-end coil end group 16r is raised, and the near-address joint portions 312-3 are covered by the distant-address joint portions 311-4, becoming less likely to be exposed to the cooling airflows blown by the fans 5. Thus, some problems have been that reductions in the size of the first stator 8 are prevented, and cooling of the first stator winding 16 deteriorates.
In an automotive alternator mounted with this first stator 8, the following problems also arise.
First, the automotive alternator increases in size with any increase in the size of the first stator 8. It is necessary to ensure clearance between the distant-address joint portions 311-4 and the near-address joint portions 312-8 and between the distant-address joint portions 311-4 and the rear bracket 2 in order to ensure electrical insulation among the joint portions 311-4 and 312-3 and the rear bracket 2, and raising the axial height of the coil end group 16r leads to additional increases in the size of the automotive alternator. In addition, ventilation resistance increases, reducing the cooling airflow rate and increasing wind noise.
In addition, since the near-address joint portions 312-3 are covered by the distant-address joint portions 311-4 and are less likely to be exposed to the cooling airflows blown by the fans 5, the temperature of the near-address joint portions 312-3 rises, leading to deterioration of the electrically-insulating coating on the conductor segments 30, and there is a risk that poor insulation will arise among the conductor segments 30, and that a decline in output will occur.
Furthermore, in the connection portion of the second conventional stator 8A, because the first near-address joint portion 312-3 joining the end portions of the continuous conductor wires 32 extending outward from Address 2 and Address 3 of the slots 15a and the second near-address joint portion 314-5 joining the end portions of the continuous conductor wires 32 extending outward from Address 4 and Address 5 of the slots 15a line up in a radial direction, and the distant-address joint portion 311-6 joining together the end portions of the continuous conductor wires 32 extending outward from Address 1 and Address 6 of the slots 15a is constructed so as to surround an outer circumferential side of the first and second near-address joint portions 312-3 and 314-5 that are lined up in the radial direction, the axial height of the connection portion is raised, and the first and second near-address joint portions 312-3 and 314-5 are covered by the distant-address joint portion 311-6, becoming less likely to be exposed to the cooling airflows blown by the fans 5. Thus, some problems have been that reductions in the size of the second stator 8A are prevented, and cooling of the second stator winding 16A deteriorates.
The present invention aims to solve the above problems and an object of the present invention is to provide a compact stator for a dynamoelectric machine having superior cooling by joining conductor wires extending outward from a slot pair separated by a predetermined number of slots, such that end portions of conductor wires extending outward from addresses of the slot pair separated by three or more addresses are joined together (a distant-address joint portion), end portions of conductor wires in the slot pair separated by two or less addresses are joined together (a near-address joint portion), and the distant-address joint portion is offset in a circumferential direction relative to the near-address joint portion, to lower an axial height of a coil end group and eliminate coverage of the near-address joint portion by the distant-address joint portion.
In order to achieve the above object, according to one aspect of the present invention, there is provided a stator for an automotive alternator including:
an annular stator core in which a plurality of slots extending axially are disposed in a circumferential direction; and
a stator winding installed in the slots, the stator winding being provided with a plurality of winding sub-portions, each of the winding sub-portions including:
slot-housed portions housed in housing positions from Address 1 to Address m (mxe2x89xa74) lined up in one row from an inner circumferential side to an outer circumferential side in each of the slots; and
coil ends in which the slot-housed portions housed in different addresses in the slots in each slot pair separated by a predetermined number of slots are connected in series outside the slots, the coil ends including:
distant-address joint portions in which the slot-housed portions housed in addresses separated by three or more addresses in the slots in the each slot pair are joined together outside the slots; and
near-address joint portions in which the slot-housed portions housed in addresses separated by two or less addresses in the slots in the each slot pair are joined together outside the slots,
wherein the distant-address joint portions are disposed so as to be separated in a circumferential direction relative to the near-address joint portions.
Each of the winding sub-portions may be constructed by inserting a plurality of conductor segments into different addresses in the slots in the each slot pair, the conductor segments each being formed into a U shape, and joining together free end portions of different conductor segments among the conductor segments extending outward from the slots from different addresses in the slots in the each slot pair, joint portions joining together the free end portions of the conductor segments being constituted by the distant-address joint portions and the near-address joint portions.
The joint portions joining together the free end portions of the conductor segments may be arranged in a circumferential direction at a first end of the stator core.
Each of the winding sub-portions may each be constructed by installing one continuous conductor wire so as to occupy different addresses in the slots at intervals of the predetermined number of slots,
the coil ends being constituted by:
turn portions of the continuous conductor wires in which different slot-housed portions among the slot-housed portions in the slots in the each slot pair are linked outside the slots; and
joint portions joining together end portions of the continuous conductor wires in which different slot-housed portions among the slot-housed portions in the slots in the each slot pair are linked outside the slots,
the joint portions joining together the end portions of the continuous conductor wires being constituted by the distant-address joint portions and the near-address joint portions.
The plurality of winding sub-portions may be constructed by installing winding assemblies in the stator core so as to be stacked in two or more layers in a slot depth direction, the winding assemblies each being formed by simultaneously folding a plurality of the continuous conductor wires, and
wherein each of the winding assemblies is constructed by arranging continuous conductor wire pairs equivalent in number to the predetermined number of slots so as to be offset by a pitch of one slot from each other, each of the continuous conductor wire pairs being composed of two of the continuous conductor wires arranged so as to be offset from each other by a pitch equivalent to the predetermined number of slots and so as to stack the slot-housed portions stacked in the slot depth direction, and the two continuous conductor wires each being formed into a pattern in which the slot-housed portions are arranged at a pitch equivalent to the predetermined number of slots and adjacent pairs of the slot-housed portions linked by the turn portions are offset so as to alternately occupy different addresses in the slots.
The near-address joint portions may be arranged in a circumferential direction so as to have a uniform axial height, and each of the distant-address joint portions may be disposed between circumferentially-adjacent pairs of the near-address joint portions at the same axial height as the near-address joint portions.
The near-address joint portions may be arranged in a circumferential direction so as to have a uniform axial height, and the distant-address joint portions may be arranged in a circumferential direction at the same axial height as the near-address joint portions at a first circumferential end of a group of the near-address joint portions arranged in the circumferential direction.
The near-address joint portions may be arranged in a circumferential direction so as to have a uniform axial height, and the distant-address joint portions may be arranged in a circumferential direction at the same axial height as the near-address joint portions at first and second circumferential ends of a group of the near-address joint portions arranged in the circumferential direction.
The near-address joint portions may be arranged in at least one row in a circumferential direction, radial positions of the distant-address joint portions aligning with at least one row of the near-address joint portions arranged in the circumferential direction.
The distant-address joint portion may be formed by directly joining together extending portions of the slot-housed portions.
The distant-address joint portion may be formed by joining together extending portions of the slot-housed portions by means of a metal connection portion.
An electrically-insulating material may be interposed in at least one position selected from a group including a position between the distant-address joint portion and the near-address joint portion, a position between two of the distant-address joint portions, and a position between two of the near-address joint portions.